1. Field of the Invention
The present invention relates generally to discarding sabot projectiles and more specifically to a clip-lock protective cap for saboted projectiles, which cap meets environmental and rough handling requirements and is still capable of reliable discard at muzzle exit.
2. Prior Art
The existing protective caps for a saboted projectile utilize a one piece approach with special seams designed to fail under high spin loads. A constant design problem arises trying to make the seams strong enough to withstand handling loads and yet weak enough to easily discard. Because such existing cap designs rely upon failure of the material for separation, discard is not a very repeatable or reliable event. Rough handling and drop tests require that the cap be able to withstand significant abuse. The ability of a cap to survive rough handling and still release during launch provides for design criteria, which in many cases are mutually exclusive. This problem is further exacerbated by the recent trend to reduce the spin rate of certain projectiles.
A patent search has failed to provide any disclosure in the prior art which satisfies the two seemingly contradictory requirements of a cap capable of withstanding rough handling while simultaneously providing repeatable and reliable separation for discard. By way of example, the following U.S. Patents are deemed to be relevant to varying degrees.
U.S. Pat. No. 3,771,458 to Schweimler et al is directed to a sabot projectile that has its core covered by a cap of plastic. The subcaliber core 2 has a nylon plastic cap 1 thereon and a sabot 3 with guide ring 4 and sabot to core coupling spring 5. After the projectile is fired and leaves the gun barrel, centrifugal force expands the coupling spring, disengaging the sabot from the core and cap 1 is destroyed by the centrifugal force.
U.S. Pat. No. 4,750,425 to Sigg et al is directed to a sabot projectile with a plastic hood. The projectile 10 with core 11, sabot tail 15, and sabot jacket 18 has fastened to the jacket a protective hood 21 of plastic anchored by means of a bead 22 in groove 23 of the jacket 18. Upon firing the projectile, the jacket 18 falls apart by failing at the thin webs 19.
U.S. Pat. No. 4,714,024 to Bocker et al is directed to a nose hood for a subcaliber projectile that is fired with the aid of a sabot. The projectile 1 has a nose 10 with a hood 14 of synthetic material glued in place. The hood has a plurality of longitudinal recesses 13 and a frontal air flow receiving surface 15. When the projectile leaves the gun barrel, pressure oscillations caused by the nose hood breaks up the sabot while the hood is being disintegrated.
U.S. Pat. No. 4,142,467 to Stahlmann et al is directed to a subcaliber projectile with a sabot and a hood. The projectile 3 has an aluminum alloy sabot 1 and polyethylene hood 2. The sabot is connected to the hood by a strong snap connection 4, a bead on the sabot engaging a groove on the hood. Two gas ducts 10 enable propellant gases to accelerate the hood relative to the projectile while in the barrel of the firearm, enabling separation when in the barrel.
U.S. Pat. No. 4,757,766 to Ruffle et al is directed to an armor penetrating ammunition assembly provided with a multi-segment aluminum protective cap. The projectile 10 with sabot 18 has a protective cap 26 with stiffening ribs, torque resisting tabs, and rolled stiffening portions. Each segment of the cap 28, 28' is attached to a corresponding segment of the sabot 19, 19'. When fired from a cannon, sabot 18 separates and the cap segments separate with the sabot segments.